The present invention is related to a discharge valve device of a rotary compressor.
A rotary compressor is installed as one component in an air conditioner cooling cycle for compressing refrigerant to create a high temperature and high pressure. A conventional rotary compressor is comprised of a housing 1, a shaft 5 which is connected to a motor 2 provided in the housing 1, a roller 7 eccentrically mounted at the lower end of the shaft 5, and a cylinder 6 enclosing the roller 7 as shown in FIG. 1. An eccentric 51 (FIG. 2) is attached to the shaft 5 and is freely movably disposed in the roller 7. As the shaft 5 is rotated by the motor 2, the roller 7 rotates in an eccentric manner to compress the refrigerant taken in through a suction pipe 3. The pressed gas is discharged from the cylinder 6 and discharges through a pipe 4 provided at the top of the housing 1.
A conventional discharge process as used in the above described rotary compressor will now be described in detail. A conventional compressing device is illustrated in FIG. 2A and FIG. 2B. Roller 7 s provided at the lower end portion of the shaft 5. A vane 8 is located in the cylinder 6 and held in continuous contact with the roller 7 by a spring 9. A suction area 6S and a discharge or compressing area 6D are generated each defined within the cylinder 6 by the vane 8, the roller 7, and an inner wall of the cylinder 6. Considering the view in FIG. 2A, the suction pipe 3 is provided on the left side of the vane 8, while the discharge port 10 is located on the right side at the top or the bottom surface of the cylinder 6. An upper and lower support plate 13, 14 are mounted on the top surface and the bottom surface of the cylinder, respectively. The upper and lower support plate 13, 14 respectively, each contain discharge passage 15. As the shaft 5 is rotated, the roller 7 rotates in an eccentric manner. The refrigerant taken in through a suction pipe 3 is compressed, and the pressed gas is discharged through the discharge port 10 and the discharge passage 15. At the exterior portions of the discharge passage 15 plate valves 11 are provided. The discharge passage 15 is opened in the discharging mode by the pressure of the refrigerant. During the suction mode and compression mode of the refrigerant, the plate valves 11 close the discharge passage 15 as a result of their own elastic character.
In the discharge mode of this type of compressor, there is a problem in that the striking contact of the returning plate valves 11 against the outer seat of the discharge passage 15 due to their elasticity and to the discharge pressure from the cylinder 6 causes vibration noises. This noise is one of the major noises produced by a compressor.
For reducing noise, Japanese Utility Model Publication Nos. 1-15911 (1989), 1-8706 (1989), and 1-37190 (1989) have been proposed. All of those valves are formed in a circular design. While each of those valves decreases in the compressor noise level and the stress on the valves, each is attended with an insufficient capacity to absorb the shocks from the high pressure discharge gas.